SkySend

S3 Storage Backend

✨ Features

• server: Added S3-compatible storage backend as alternative to local filesystem storage
• server: Added STORAGE_BACKEND environment variable to switch between filesystem (default) and s3 storage
• server: Added S3 configuration via environment variables (S3_BUCKET, S3_REGION, S3_ENDPOINT, S3_ACCESS_KEY, S3_SECRET_KEY, S3_FORCE_PATH_STYLE, S3_PRESIGNED_EXPIRY, S3_PUBLIC_URL)
• server: Uploads in S3 mode stream directly to S3 via multipart upload without disk buffering on the server
• server: Added S3_PUBLIC_URL for direct download URLs via R2 custom domains or public buckets - avoids presigned URL complexity and CORS issues
• server: Falls back to presigned URLs when S3_PUBLIC_URL is not set (for private buckets)
• web: Client download logic transparently handles both direct file streams (filesystem), presigned URL redirects (S3 private), and public URL redirects (S3 public)
• server: Supports all S3-compatible providers (AWS S3, Cloudflare R2, Hetzner Object Storage, MinIO, Wasabi, Backblaze B2, DigitalOcean Spaces, and more) via custom endpoint configuration
• server: Logs storage mode on startup (filesystem path or S3 endpoint with public/presigned mode)
• server: S3 connectivity test on startup - verifies bucket access, write, and delete permissions before accepting requests
• server: Added S3_PART_SIZE and S3_CONCURRENCY environment variables for tuning S3 upload throughput
• web: Download progress bar now shows real-time download speed (e.g. 42.5 MB/s) alongside the percentage, matching the upload speed display

🐛 Bug Fixes

• docker: Fixed Docker healthcheck showing unhealthy despite a running server - replaced wget (not available in Alpine) with Node.js fetch and increased start period to 30s
• web: Upload progress bar now reflects actual end-to-end upload progress instead of encryption speed - progress updates after each chunk is fully uploaded (including server-to-S3 forwarding)

🔒 Security

• server: CSP connect-src header is dynamically extended to allow client fetches to the configured S3 endpoint

🎨 Improvements

• server: Introduced StorageBackend interface with adapter pattern for pluggable storage implementations
• server: Optimized S3 multipart upload performance - configurable part size (default 25MB) and parallel part uploads (default 4 concurrent) to reduce round-trip overhead

📝 Documentation

• docs: Added S3 storage backend section to environment variables reference with configuration table, S3_PUBLIC_URL, and provider examples (R2, MinIO)
• docs: Added S3 variable definitions to developer environment reference (STORAGE_BACKEND, S3_BUCKET, S3_REGION, S3_ENDPOINT, S3_ACCESS_KEY, S3_SECRET_KEY, S3_FORCE_PATH_STYLE, S3_PRESIGNED_EXPIRY, S3_PUBLIC_URL, S3_PART_SIZE, S3_CONCURRENCY)
• docs: Updated architecture diagram and data storage section to reflect S3 backend and download flow
• docs: Added S3 CORS configuration guide with examples for Cloudflare R2, AWS S3, and MinIO
• docs: Added S3 Docker Compose example with S3_PUBLIC_URL to self-hosting guide
• docs: Updated data backups guide with S3 storage note
• docs: Added S3 storage mention to README and docs homepage feature cards

🐳 Docker

• Image: skyfay/skysend:v2.2.0
• Also tagged as: latest, v2
• Platforms: linux/amd64, linux/arm64